X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FBranchProbabilityInfo.cpp;h=bbd87505952216d88b8cad5f042b36e03ecf7288;hb=cc9916444881b06a35ae6402d37a4e38a56dfd52;hp=54c148ed29303cb0817a6b010ecd4e9e63a38bcf;hpb=77226a03dca98e6237c1068f2652fe41bea7b687;p=oota-llvm.git

diff --git a/lib/Analysis/BranchProbabilityInfo.cpp b/lib/Analysis/BranchProbabilityInfo.cpp
index 54c148ed293..bbd87505952 100644
--- a/lib/Analysis/BranchProbabilityInfo.cpp
+++ b/lib/Analysis/BranchProbabilityInfo.cpp
@@ -14,16 +14,18 @@
 #include "llvm/Analysis/BranchProbabilityInfo.h"
 #include "llvm/ADT/PostOrderIterator.h"
 #include "llvm/Analysis/LoopInfo.h"
+#include "llvm/IR/CFG.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Metadata.h"
-#include "llvm/Support/CFG.h"
 #include "llvm/Support/Debug.h"
 
 using namespace llvm;
 
+#define DEBUG_TYPE "branch-prob"
+
 INITIALIZE_PASS_BEGIN(BranchProbabilityInfo, "branch-prob",
                       "Branch Probability Analysis", false, true)
 INITIALIZE_PASS_DEPENDENCY(LoopInfo)
@@ -151,8 +153,8 @@ bool BranchProbabilityInfo::calcUnreachableHeuristics(BasicBlock *BB) {
 
   uint32_t UnreachableWeight =
     std::max(UR_TAKEN_WEIGHT / (unsigned)UnreachableEdges.size(), MIN_WEIGHT);
-  for (SmallVector<unsigned, 4>::iterator I = UnreachableEdges.begin(),
-                                          E = UnreachableEdges.end();
+  for (SmallVectorImpl<unsigned>::iterator I = UnreachableEdges.begin(),
+                                           E = UnreachableEdges.end();
        I != E; ++I)
     setEdgeWeight(BB, *I, UnreachableWeight);
 
@@ -161,8 +163,8 @@ bool BranchProbabilityInfo::calcUnreachableHeuristics(BasicBlock *BB) {
   uint32_t ReachableWeight =
     std::max(UR_NONTAKEN_WEIGHT / (unsigned)ReachableEdges.size(),
              NORMAL_WEIGHT);
-  for (SmallVector<unsigned, 4>::iterator I = ReachableEdges.begin(),
-                                          E = ReachableEdges.end();
+  for (SmallVectorImpl<unsigned>::iterator I = ReachableEdges.begin(),
+                                           E = ReachableEdges.end();
        I != E; ++I)
     setEdgeWeight(BB, *I, ReachableWeight);
 
@@ -222,9 +224,7 @@ bool BranchProbabilityInfo::calcColdCallHeuristics(BasicBlock *BB) {
 
   // Determine which successors are post-dominated by a cold block.
   SmallVector<unsigned, 4> ColdEdges;
-  ColdEdges.reserve(TI->getNumSuccessors());
   SmallVector<unsigned, 4> NormalEdges;
-  NormalEdges.reserve(TI->getNumSuccessors());
   for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
     if (PostDominatedByColdCall.count(*I))
       ColdEdges.push_back(I.getSuccessorIndex());
@@ -253,8 +253,8 @@ bool BranchProbabilityInfo::calcColdCallHeuristics(BasicBlock *BB) {
 
   uint32_t ColdWeight =
       std::max(CC_TAKEN_WEIGHT / (unsigned) ColdEdges.size(), MIN_WEIGHT);
-  for (SmallVector<unsigned, 4>::iterator I = ColdEdges.begin(),
-                                          E = ColdEdges.end();
+  for (SmallVectorImpl<unsigned>::iterator I = ColdEdges.begin(),
+                                           E = ColdEdges.end();
        I != E; ++I)
     setEdgeWeight(BB, *I, ColdWeight);
 
@@ -262,8 +262,8 @@ bool BranchProbabilityInfo::calcColdCallHeuristics(BasicBlock *BB) {
     return true;
   uint32_t NormalWeight = std::max(
       CC_NONTAKEN_WEIGHT / (unsigned) NormalEdges.size(), NORMAL_WEIGHT);
-  for (SmallVector<unsigned, 4>::iterator I = NormalEdges.begin(),
-                                          E = NormalEdges.end();
+  for (SmallVectorImpl<unsigned>::iterator I = NormalEdges.begin(),
+                                           E = NormalEdges.end();
        I != E; ++I)
     setEdgeWeight(BB, *I, NormalWeight);
 
@@ -323,12 +323,15 @@ bool BranchProbabilityInfo::calcLoopBranchHeuristics(BasicBlock *BB) {
       InEdges.push_back(I.getSuccessorIndex());
   }
 
+  if (BackEdges.empty() && ExitingEdges.empty())
+    return false;
+
   if (uint32_t numBackEdges = BackEdges.size()) {
     uint32_t backWeight = LBH_TAKEN_WEIGHT / numBackEdges;
     if (backWeight < NORMAL_WEIGHT)
       backWeight = NORMAL_WEIGHT;
 
-    for (SmallVector<unsigned, 8>::iterator EI = BackEdges.begin(),
+    for (SmallVectorImpl<unsigned>::iterator EI = BackEdges.begin(),
          EE = BackEdges.end(); EI != EE; ++EI) {
       setEdgeWeight(BB, *EI, backWeight);
     }
@@ -339,7 +342,7 @@ bool BranchProbabilityInfo::calcLoopBranchHeuristics(BasicBlock *BB) {
     if (inWeight < NORMAL_WEIGHT)
       inWeight = NORMAL_WEIGHT;
 
-    for (SmallVector<unsigned, 8>::iterator EI = InEdges.begin(),
+    for (SmallVectorImpl<unsigned>::iterator EI = InEdges.begin(),
          EE = InEdges.end(); EI != EE; ++EI) {
       setEdgeWeight(BB, *EI, inWeight);
     }
@@ -350,7 +353,7 @@ bool BranchProbabilityInfo::calcLoopBranchHeuristics(BasicBlock *BB) {
     if (exitWeight < MIN_WEIGHT)
       exitWeight = MIN_WEIGHT;
 
-    for (SmallVector<unsigned, 8>::iterator EI = ExitingEdges.begin(),
+    for (SmallVectorImpl<unsigned>::iterator EI = ExitingEdges.begin(),
          EE = ExitingEdges.end(); EI != EE; ++EI) {
       setEdgeWeight(BB, *EI, exitWeight);
     }
@@ -400,10 +403,24 @@ bool BranchProbabilityInfo::calcZeroHeuristics(BasicBlock *BB) {
     // InstCombine canonicalizes X <= 0 into X < 1.
     // X <= 0   ->  Unlikely
     isProb = false;
-  } else if (CV->isAllOnesValue() && CI->getPredicate() == CmpInst::ICMP_SGT) {
-    // InstCombine canonicalizes X >= 0 into X > -1.
-    // X >= 0   ->  Likely
-    isProb = true;
+  } else if (CV->isAllOnesValue()) {
+    switch (CI->getPredicate()) {
+    case CmpInst::ICMP_EQ:
+      // X == -1  ->  Unlikely
+      isProb = false;
+      break;
+    case CmpInst::ICMP_NE:
+      // X != -1  ->  Likely
+      isProb = true;
+      break;
+    case CmpInst::ICMP_SGT:
+      // InstCombine canonicalizes X >= 0 into X > -1.
+      // X >= 0   ->  Likely
+      isProb = true;
+      break;
+    default:
+      return false;
+    }
   } else {
     return false;
   }
@@ -471,6 +488,8 @@ void BranchProbabilityInfo::getAnalysisUsage(AnalysisUsage &AU) const {
 }
 
 bool BranchProbabilityInfo::runOnFunction(Function &F) {
+  DEBUG(dbgs() << "---- Branch Probability Info : " << F.getName()
+               << " ----\n\n");
   LastF = &F; // Store the last function we ran on for printing.
   LI = &getAnalysis<LoopInfo>();
   assert(PostDominatedByUnreachable.empty());
@@ -542,7 +561,7 @@ isEdgeHot(const BasicBlock *Src, const BasicBlock *Dst) const {
 BasicBlock *BranchProbabilityInfo::getHotSucc(BasicBlock *BB) const {
   uint32_t Sum = 0;
   uint32_t MaxWeight = 0;
-  BasicBlock *MaxSucc = 0;
+  BasicBlock *MaxSucc = nullptr;
 
   for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
     BasicBlock *Succ = *I;
@@ -562,7 +581,7 @@ BasicBlock *BranchProbabilityInfo::getHotSucc(BasicBlock *BB) const {
   if (BranchProbability(MaxWeight, Sum) > BranchProbability(4, 5))
     return MaxSucc;
 
-  return 0;
+  return nullptr;
 }
 
 /// Get the raw edge weight for the edge. If can't find it, return
@@ -579,6 +598,11 @@ getEdgeWeight(const BasicBlock *Src, unsigned IndexInSuccessors) const {
   return DEFAULT_WEIGHT;
 }
 
+uint32_t BranchProbabilityInfo::getEdgeWeight(const BasicBlock *Src,
+                                              succ_const_iterator Dst) const {
+  return getEdgeWeight(Src, Dst.getSuccessorIndex());
+}
+
 /// Get the raw edge weight calculated for the block pair. This returns the sum
 /// of all raw edge weights from Src to Dst.
 uint32_t BranchProbabilityInfo::